Homer is shocked to discover that his neighbor and bowling teammate Dan Gillick is an accountant for Fat Tony and his mob. When the government finally catches up with Fat Tony and he is forced to serve jury duty, he names Dan as his temporary replacement. Dan gradually becomes power-hungry from the position, which frightens him. When Fat Tony orders him to carry out a murder, he begs Homer to do anything to stop him. Homer ties Dan to a chair in the basement, but Dan escapes and starts hunting down Fat Tony's associates, only to be inadvertently thwarted by Homer before he can kill any of them. Once the trial ends and Fat Tony is released from jury duty, he regains control of the mob. As Homer and Dan struggle over Dan's gun, it discharges a bullet into the Kwik-E-Mart, wounding Snake Jailbird - who had just been acquitted in the trial on which Fat Tony served - as he tries to rob it. Dan opens an ear-piercing stand in the Springfield Mall, commenting that he loves the job because he gets to use an ear-piercing gun.
Meanwhile, Lisa passes out during a saxophone solo at a school concert. She is diagnosed with iron deficiency and decides to add insects to her vegetarian diet in order to combat it. Although she enjoys the addition to her diet at first, the bugs start to taunt her in her dreams, prompting her to quit eating insects. She decides to release the grasshoppers she has been raising into the wild, but Bart accidentally breaks the aquarium holding them and they escape into the basement instead. They later swarm over Dan, tied up in the basement, and his screams prompt Homer to cut him loose, allowing him to flee. The grasshoppers are later rounded up and released alongside a country road, where they immediately eat a nearby corn maze down to the ground.